Can't find one that is less than 30 feet long... (for having all of this in the rack)
The cable is not all that bulky, and rather to much than not enough (as far as data) audio that's different.
I think some of your choices might be:
Order the cable and live with it a few weeks and if you find it to long take it to a local tech to shorten it. A local guy can probably just build you one also, but it will be more than $20.
Or
Order the box from RJM this way you have your choice of midi cable lengths, but keep in mind its going to require space in your rack, the box is roughly the same size as a stomp box and you are going to have three connections coming out of it 1) the power supply 2) midi to your Mastermind LT 3) midi to the Axe Fx
Or
Write Fractal support, tell them you have a Mastermind LT, tell them the device draws 150mA (as per there website)and tell them the output for the power supply that came with the LT (something you did not get back to us on
) You may get Fractals blessing to use it the way you want!
The cable is still my vote as
@iaresee pointed out the power supply is going through a few diodes, better to be safe. (unless Fractal states otherwise) I was not aware of this till it was pointed out,
John